Unable to setup an account in mail for my .mac address

I have had a .mac email address for years but have not been able to get it set up in mail for some time on any machine or phone.

I go into accounts, add new account, enter email address (which is the one for my apple id) and my apple id password which I have treble checked is the correct one and I get "Unable to verify account name or password".

Are .mac email addresses obsolete? Is there a different password for the email and apple id? If so where do I change it and if it depends on my getting emails to the .mac address that is not going to work.

Do I have to create an icloud email and if so do I then have to go an change the email on my apple id to the icloud email and change all the logins where I have used the .mac address?

Spent the afternoon on this task that should be soooo simple and admitting defeat. Anyone any suggestions or information?